Avocado-derived biomass: Chemical composition and antioxidant potential potential Minerva C. García Vargas, María del Mar Contreras, Irene Gómez-Cruz, Juan Miguel Romero-García, Eulogio Castro
Content • Introduction and objective • Methods • Results • Results • Characteristics and elemental composition • Chemical characterization • Total phenolic and flavonoid content and antioxidant activity • Conclusions 2
Production quantities of avocados by country Production quantities of avocados by country, average 1994 - 2018 average 1994 - 2018 Source: FAOSTAT, April 1, 2020 Top 10 producers average 1994-2018 Introduction Methods Conclutions Results 3
Avocado can be better exploited Avocado oil extraction Avocado can be Guacamole better exploited if Sorting avacados (quality/ripen) Sorting avacados the residual parts (quality/ripen) Washing Washing are used as water waste Peel 100% Washing alternative source Partial peeling Peel 90% of value-added Stone 100% Peeling Stone 100% Destoning compounds from the structural and Crushing Crushing Destoning Destoning non-structural Kneading chemical fraction malaxing Mixed Decanter Water Pulp + peel extraction High pressure packaging Oil polishing Oil recovery from water Packed guacamole Clean oil Waste-water Waste-water Clean oil Cold pressed avocado oil Waste-water Introduction Methods Conclutions Results 4
Objective In this work, to enable a complete valorization of avocado peel and stone in multiple bioproducts, the chemical composition was determined, as well as their phenolic content and antioxidant activity were studied using food grade solvents. Antioxidants Other valuable chemical components Introduction Methods Conclutions Results
Methods Moisture Ash Elemental analysis Soxhlet extraction Total phenol content Total (hexane) lipids Total flavonoids content Antioxidant activity Avocado (TEAC and FRAP) Aqueous peel and extract stone Sugars Acid hydrolysis (air dried) (air dried) (mono, di and (mono, di and oligomeric) Liquid Total phenol content extract Total flavonoids content Ethanolic Soxhlet extract Antioxidant activity (TEAC and extraction FRAP) (water- ethanol) Acid soluble lignin Liquid fraction Sugars (polymeric) Extracted Acid solid hydroly Acid insoluble lignin sis Solid fraction Ash Methods Conclutions Introduction Results 6
Methods Moisture Moisture and ash were determined by gravimetric analysis. Ash Hydrogen, Carbon, Nitrogen and Sulfur were determined by elemental analysis. Elemental analysis Total phenolic and flavonoid content Total phenol content Soxhlet extraction Total were measured using the Folin-Ciocalteu (hexane) lipids colorimetric assay and the aluminum Total flavonoids content chloride colorimetric methods, respectively. Antioxidant activity (TEAC and FRAP) Avocado peel Aqueous and stone extract Sugars Acid hydrolysis let measure Acid hydrolysis (air dried) (mono, di and (mono, di and sugars by high-performance sugars by high-performance oligomeric) liquid chromatography (HPLC) Liquid Total phenol content Antioxidant activity was appraise by the extract ability to scavenge cation ABTS• + and Total flavonoids content Fe 2+ using the Trolox equivalent Ethanolic Soxhlet antioxidant capacity (TEAC) and ferric extract Antioxidant activity (TEAC and FRAP) extraction ion reducing antioxidant power (FRAP) (water- ethanol) Acid soluble lignin Acid soluble lignin was determined by spectrophotometry at 205 nm Liquid fraction Biomass was firstly Sugars (polymeric) Extracted extracted with water using solid Acid hydrolysis Soxhlet extraction and Acid insoluble lignin was determined Acid insoluble lignin by gravimetric analysis after a two- secondly with ethanol to Solid fraction obtain two liquid fractions step acid hydrolysis of the extracted Ash solid from the Soxhlet extraction (aqueous and ethanolic extracts) and a solid fraction Methods Conclutions Introduction Results 7
Characteristics and elemental composition Pulp 73%, f.w. Stone 14%, f.w. 13%, f.w. Peel Element % Element % Peel Peel Stone Stone Element % Element % Peel Peel Stone Stone N 0.97 ± 0.07 0.66 ± 0.01 H 5.71 ± 0.02 5.58 ± 0.02 C 49.83 ± 0.42 42.05 ± 0.05 O 42.2 ± 2.62 50.79 ± 1.56 Ash 3.81 ± 0.05 2.76 ± 0.28 Humidity 70.9± 0.2 52.0 ± 0.4 •Avocado peel and stone presented similar elemental composition, but peel contained slightly higher percentages of N and O. •For its use as biofuel for domestic or industrial heating, some limitations are the ash content and the humidity compared to other biomasses, especially, for peel. Results Conclutions Introduction Methods 8
Chemical Characterization 50 45 40 35 Avocado peel 30 Avocado stone % 25 20 15 10 5 0 Protein Glucose Xilose Galactose Arabinose Acid soluble Acid Aqueous Ethanolic Lipids lignin insoluble extractives extractives (hexanic lignin extractives) Valorization of lignin and sugars from the structural fraction is of interest given the high content, which could be used to obtain biofuels, such as ethanol and buthanol, or derivatives with industrial relevance. Results Conclutions Introduction Methods 9
Total phenolic (TPC) and flavonoid content (TFC) and Antioxidant activity Part TPC TFC TEAC FRAP AE EE AE EE AE EE AE EE In terms of biomass weight (g GAE or g rutin or mmol TE/100 g, d.w.) 4.13 0.60 5.35 0.75 17.48 0.47 15.20 1.49 AP ±0.56 ±0.12 ±1.36 ±0.09 ±3.12 ±0.05 ±2.02 ±0.34 0.31 0.18 0.45 0.67 1.66 0.32 1.29 0.66 AS AS ±0.06 ±0.06 ±0.03 ±0.03 ±0.13 ±0.13 ±0.02 ±0.02 ±0.31 ±0.31 ±0.08 ±0.08 ±0.32 ±0.32 ±0.05 ±0.05 In terms of extract weight (g GAE or g rutin or mmol TE/100 g, d.w.) 26.56 12.60 34.23 15.63 112.15 9.67 97.78 37.77 AP ±2.77 ±3.17 ±6.90 ±1.25 ±13.35 ±2.11 ±7.83 ±1.68 1.81 4.39 2.66 16.49 9.85 7.84 7.71 16.31 AS ±0.34 ±0.88 ±0.82 ±0.80 ±2.03 ±2.04 ±1.93 ±1.62 AE, aqueous extract; AP, avocado peel; AS, avocado stone; EE, ethanolic extract; GAE, gallic acid equivalents; TE, trolox equivalents. Total phenolic content (TPC); Total flavonoids content (TFC) and Antioxidant Activity determined by TEAC and FRAP assays •The extractive fraction of the peels contained the highest amount of phenolic compounds (4.7 g/100 g biomass), mainly, concentrated in the aqueous fraction (i.e. 87%) compared to the ethanol one, which was subsequently extracted. • It correlated with a major antioxidant activity. Results Conclutions Introduction Methods 10
Conclusions • Avocado peel and stone have a high potential to obtain various valuable compounds from their chemical composition in a biorefinery context. • Stone is rich in glucose from the polymeric fraction • Stone is rich in glucose from the polymeric fraction and peel in lignin. • Peel is a rich source of antioxidants. • This could generate an extra income before, for example, burning or disposal with no industrial benefits. Conclusions Introduction Methods Results 11
Acknowledgments Authors thank the FEDER UJA projects 1260905 funded by “Programa Operativo FEDER 2014-2020” and “Consejería de Economía y Conocimiento de la Junta de Andalucía”. I.G.-C. expresses her gratitude to the University of Jaén for the grant R5/04/2017 and and M.C.G.V. for the grant “Beca-comisión para estadía técnica del Tecnológico Nacional de México/Instituto Tecnológico de Zitácuaro y Universidad de Jaén”. Some of the components in Figures are made with the help of images by Some of the components in Figures are made with the help of images by Pixabay. 12
Thank you for your attention “Somewhere, something incredible is waiting to be known.” ― Carl Sagan Minerva C. García Vargas 1;#,* , María del Mar Contreras 2,#,* , Irene Gómez-Cruz 2 , Juan Miguel Romero-García 2 , Eulogio Castro 2 1 Tecnológico Nacional de México / Instituto Tecnológico de Zitácuaro; minerva.gv@zitacuaro.tecnm.mx (M.C.G.V.) 2 Department of Chemical, Environmental and Materials Engineering, Universidad de Jaén, Jaén, Spain; mcgamez@ujaen.es (M.D.M.C.); igcruz@ujaen.es (I.G.-C.); jrgarcia@ujaen.es (J.M.R.G); ecastro@ujaen.es (E.C.G) 13
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